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Procedure 19 | Resection of Intradural Intramedullary or Extramedullary Spinal Tumors 177
Evidence
Berhouma M, Bahri K, Houissa S, et al. Management of intramedullary spinal cord
tumors: surgical considerations and results in 45 cases. Neurochirurgie
2009;55:293-302.
Biswas A, Puri T, Goyal S, et al. Spinal intradural primary germ cell tumour—
review of literature and case report. Acta Neurochir 2009;151:277-84.
Brotchi J. Intrinsic spinal cord tumor resection. Neurosurgery 2002;50:1059-66.
Burger PC, Scheithauer BW. Tumors of the central nervous system. In: Rosai J,
Sobin LH, editors. Atlas of Tumor Pathology, series 3, facs 10. Washington, DC:
Armed Forces Institute of Pathology; 1994.
Cavalcanti DD, Martirosyan NL, Verma K, et al. Surgical management and
outcome of schwannomas in the craniocervical region. J Neurosurg
2010;114:1257-67.
Constantini S, Miller DC, Allen JC, et al. Radical excision of intramedullary spinal
cord tumors: surgical morbidity and long-term follow-up evaluation in 164
children and young adults. J Neurosurg Spine 2000;93:183-93.
Dong-Ki Ahn, Hoon-Seok Park, Daw-Jung Choi, et al. The surgical treatment for
spinal intradural extramedullary tumors. Clin Orthop Surg 2009;1:165-72.
Epstein FJ, Farmer JP, Freed D. Adult intramedullary astrocytomas of the spinal
cord. J Neurosurg 1992;77:355-9.
Mechtler L, Cohen ME. Clinical presentation and therapy of spinal tumors. In:
Bradley WG, Daroff RB, Fenchel GM, Marsden CD, editors. Neurology in Clinical
Practice: The Neurological Disorders, 2nd ed. Boston: Butterworth-Heinemann;
1996.
Osborn AG. Diagnostic Neuroradiology. St Louis: Mosby–Year Book; 1994.
Simeone FA. Intradural tumors. In: Rothman RH, Simeone FA, editors. The Spine,
3rd ed. Philadelphia: WB Saunders; 1992.
P R O C ED U R E 2 0
Endoscopic Thoracic
Diskectomy
Stepan Kasimian and J. Patrick Johnson
I N D I CAT I O NS P I T F A L L S
• Steep learning curve
• Asymptomatic level with multilevel disk
disease
• History of structural lung disease
• Poor tolerance of single-lung ventilation
C O N T RO V E R S IE S
• The use of navigation systems has been
shown to facilitate operation (Holly
et al, 2001).
• Posterolateral approaches, such as a
transpedicular or costotransversectomy
approach, could address a ventral
herniation; however, these approaches
are ideal for paracentral lesions
(Johnson et al, 2000).
• A multilevel procedure may be better
undertaken with thoracotomy because
of longer operative time with
thoracoscopy.
• A preoperative angiogram has been
recommended to determine location of
the artery of Adamkiewicz (Di Chiro
et al, 1970). However, for a thoracic
diskectomy, ligation of a segmental
artery is rarely necessary.
• Fusion may be necessary when
excessive disk material is removed or
the spine is otherwise destabilized.
Indications
n
The indications for thoracoscopic diskectomy are similar to the indications for
other procedures to treat central thoracic disk herniations.
• Ventral herniated thoracic disk, causing myelopathy, gait disturbance, lower
extremity weakness, or loss of sphincter control
• Thoracic disk herniation with axial back pain, thoracic radiculopathy, or leg
pain that has failed conservative care (injections, nonsteroidal antiinflammatory drugs, physiotherapy, etc.)
n
Thoracoscopic spinal surgery may also be performed for nerve sheath tumor
resection, anterior release for scoliosis, sympathectomy for hyperhidrosis, or
vertebral corpectomy. Figure 20-1 shows a 55-year-old female patient with an
incidental finding of a mediastinal mass on a chest radiograph. An axial computed tomography (CT) scan (see Figure 20-1, A), as well as axial (see Figure
20-1, B) and sagittal (see Figure 20-1, C ) magnetic resonance imaging (MRI),
showed a dumbbell-shaped tumor (peripheral nerve sheath tumor) of a nerve
root with expansion of the neuroforamen. The tumor was successfully removed
with simultaneous posterior and thoracoscopic excision.
Examination/Imaging
n
Symptoms of a thoracic herniated disk correlate with thoracic radiculopathy,
thoracic back pain, myelopathy, or vague nondermatomal leg pain (Anand and
Regan, 2002).
n
Selective thoracic nerve root blocks can be performed for therapeutic and diag-
nostic purposes, although no long-term pain relief has been shown in the literature. MRI has superior soft tissue detail and can show cord compression in
multiple planes. The authors recommend obtaining an MRI of the lumbar spine
with sagittal views of the thoracolumbar junction to compare with the thoracic
MRI. This facilitates intraoperative localization.
n
In very challenging patients with poor anatomic localization, midthoracic lesions
with little anatomic cues, or obvious vertebral body deformation, percutaneous
placement of a radiopaque marker (Guglielmi detachable coil) in the pedicle
adjacent to the disk in question can be performed preoperatively using CT guidance from a dorsal approach (Binning and Schmidt, 2010).
• Figure 20-2 shows a patient who presented with myelopathy. Sagittal (see
Figure 20-2, A) and axial (see Figure 20-2, B) T2-weighted MRI showed a
midline central disk herniation with severe cord compression. A ventral
approach is required for safe decompression.
All images in this chapter are courtesy J. Patrick Johnson, MD; from Johnson JP, Rogers CD.
Thoracoscopic diskectomy. In: Kim DH, Fessler RG, Regan JJ, editors: Endoscopic Spine Surgery
and Instrumentation. New York: Thieme; 2005.
Procedure 20 | Endoscopic Thoracic Diskectomy 179
A
C
B
FIGURE 20-1, A-C
A
FIGURE 20-2, A-B
B
180 Procedure 20 | Endoscopic Thoracic Diskectomy
FIGURE 20-3
A B
FIGURE 20-4, A-B
T R E A T M E N T OP T I O N S
• Open thoracotomy and excision of
central disk herniation through
transthoracic approach (Figure 20-6, A)
• Posterolateral approach for lateral
calcified disk herniation or central soft
disk herniation: transpedicular or
transfacet pedicle-sparing approaches
(Figure 20-6, B)
• Other methods of treatment for ventral
disk herniation include lateral
extracavitary and costotransversectomy
approaches (Bohlman and Zdeblick,
1988) (Figure 20-6, C ).
• Figure 20-3 shows an acute herniated soft disk with significant spinal cord
n
CT scans define the bony detail and a calcified disk better than MRI.
• Figure 20-4 compares a T1-weighted MR image (see Figure 20-4, A) and a
• In Figure 20-5, a large paracentral calcified disk herniation with progressive
n
High-quality plain radiographs of the lumbar spine and thoracic spine with
overlapping views of the thoracolumbar junction are needed to confirm level.
This can be important in patients with anomalous thoracic vertebrae (e.g., 13
thoracic vertebrae).
compression on T2-weighted MRI.
CT scan (see Figure 20-4, B) of a calcified paracentral disk herniation causing
thoracic radiculopathy. Note the improved delineation of the calcified paracentral disk with CT.
myelopathy is well seen with CT (see Figure 20-5, A) and sagittal reconstruction (see Figure 20-5, B).
Procedure 20 | Endoscopic Thoracic Diskectomy 181
A
FIGURE 20-5, A-B
A N AT O M Y PE A R L S
• Use a bed with a break to allow lateral
bending of the patient, to open the rib
interspaces in small patients.
• Position the patient parallel to the room
architecture.
• Check fluoroscopy before making the
incision to ensure adequate imaging of
appropriate level.
• Many radiologists will localize a thoracic
lesion using the cervical spine and
counting caudad. This can lead to
wrong-level surgery, because
intraoperative confirmation of the level
is usually performed using the lumbar
spine and thoracolumbar junction and
the ribs. Therefore the authors suggest
obtaining high-quality radiographs and
MR images of the lumbar spine, with
visualization of the thoracolumbar
junction, and relating the anatomic
nuances (osteophyte, disk collapse,
short rib, etc.) to the thoracic imaging.
• Prepare the ipsilateral iliac crest, in case
a fusion procedure is necessary.
• Ensure that the table can easily tilt
anteriorly, to aid in lung retraction.
• The Trendelenburg position can
facilitate hemostasis.
• Poor positioning of monitors can hinder
vision and flow of the operation.
• If there is a history of previous thoracic
surgery, strongly consider entering the
chest from the contralateral side to
avoid adhesions and scar tissue.
• Vacuum sand bag, intraoperative
monitoring wires, and bed attachments
in line with the fluoroscope may hinder
high-quality intraoperative images.
B
A
B
C
FIGURE 20-6, A-C
Surgical Anatomy
n
The neurovascular bundle runs on the inferior border of the rib. The rib heads
are more cephalad (i.e., closer to the disk space) in the cephalad levels. Above
T10, a complete rib head resection may be needed to expose the disk space
(Johnson et al, 2000; Moro et al, 2004).
n
For a T7-8 diskectomy, the T8 rib head should be resected.
n
The disk space is cephalad to the pedicle.
n
The artery of Adamkiewicz is usually on the left and between T9 and L3.
n
Segmental vessels are located in the midportion of the vertebral body. For a
diskectomy, these can be moved aside or coagulated, if necessary.
n
The diaphragm can be injured if portal entry is below T7.
182 Procedure 20 | Endoscopic Thoracic Diskectomy
FIGURE 20-7
C O N T RO V E R S IE S
• Positioning the patient for either a
left- or right-sided approach has been
described.
• The thick and resilient aorta is less
prone to injury on the left compared
with the azygos system; however, in
lower thoracic approaches, the liver
may interfere with right-sided exposure.
P O S I TI O N I N G EQ U I P M EN T
• A standard radiolucent table with a
kidney rest is used; break table to open
rib interspace, if necessary.
• Bolsters that attach to the table may
assist with lateral positioning; however,
pillows, straps, and tape are sufficient.
E N D O SC O P I C E QU I P M E NT
• 15-mm soft portals
• Endoscope with conventional 5- or
10-mm lenses with 0-, 30-, or 45degree angles (Figure 20-9, A); angled
scopes prevent “fencing” within the
chest (30 degree angled scope is ideal)
• Standard illumination source, camera
attachment, and video monitor
• Pneumatic drill with a long shaft
(25 cm) and pistol grip for rotational
control (Figure 20-9, B)
• Coarse diamond burr or large round
burr (5 mm) (Figure 20-9, C )
• Long-shaft Kerrison rongeurs, Cobb
elevators, pituitaries, and curettes
(
Figure 20-9, D)
• Endoscopic cotton-tipped applicators
• Harmonic scalpel (Ethicon Endo-Surgery,
Cincinnati, Ohio)
• Long-shaft Fraser suction
• Endoscopic fan blade for retraction of
the lung
Positioning
n
Give prophylactic antibiotics for gram-positive organism coverage.
n
The proper surgical team, anesthesiologist, and monitoring setup are crucial.
n
Apply antithromboembolic stockings and sequential pneumatic compression.
n
A double-lumen endotracheal tube is placed for single-lung ventilation.
n
The patient is placed in the lateral decubitus position, with the ventilated lung
down (Figure 20-7). The arm is held in an “airplane”-type holder to expose the
chest wall.
n
Pad all bony prominences and superficial nerves (e.g., peroneal and ulnar
nerves).
n
Prepare the patient for possible thoracotomy. Also, prepare the patient’s back
for a possible simultaneous posterior approach.
n
The surgeon and assistant should stand on the abdominal side of the patient.
A second assistant can stand on the back side of the patient, in case extra
instruments are necessary (Figure 20-8).
n
The monitors should be on both sides of the patient, directly facing the surgeon,
assistants, and operating room technician.
Portals/Exposures
n
Three to four portals are usually sufficient to insert the endoscope, retractor, and
suction-irrigation instrument and to perform the diskectomy.
n
Portal placement should proceed with an incision centered on the rib and blunt
dissection over the superior border (Figure 20-10).
n
The main working portal should be placed in the posterior axillary line, perpen-
dicular to the pathologic location (Figure 20-11, A and B). However, the first
portal should be above the sixth or seventh rib to avoid the diaphragm. Insert
the other portals under direct visualization.
n
Two to three other accessory portals can be placed in the anterior axillary line,
cephalad and caudad to the main working portal, to triangulate within the chest
(see Figure 20-11).
n
The perpendicular portal is usually where the drill and rongeurs are inserted,
but all the portals can be used for passing various instruments to proceed with
the diskectomy safely.
P O S I TI O N I N G PI T FA L L S
• The lung should be retracted cautiously
to allow exposure to the spine.
• Portals not centered over the lesion will
hinder adequate decompression.
• The diaphragm can be injured with
portals below T7.
P O RTA L S / E X P O S U R ES
I N S T RU M E N T A T I O N
• A trocar device is needed for
penetrating the tough muscular
abdominal wall (see Figure 20-10).
P O RTA L S / E X P O S U R ES
C O N T RO V E R S IE S
• Soft portals are less likely to cause
thoracic neuritis, but hard portals are
less likely to collapse and may facilitate
introduction and withdrawal of
instruments.
Video
monitor
Procedure 20 | Endoscopic Thoracic Diskectomy 183
Anesthesia
machines
Primary
surgeon
2nd
assistant
Assistant
Video monitor
Scrub
assistant
FIGURE 20-8
C
A
B
FIGURE 20-9, A-D
D
184 Procedure 20 | Endoscopic Thoracic Diskectomy
P O RTA L S / E X P O S U R ES
P E A R LS
• The disk space and proximal rib head
are colinear and can keep the surgeon
oriented.
• The neural foramen contains epidural
fat that can be used to indicate
proximity of the nerve root.
• To ensure the appropriate operative
level, intraoperative fluoroscopy or
radiograph of a metallic instrument
overlying the disk space should be
compared with preoperative
radiographs and MRI scans.
P O RTA L S / E X P O S U R ES
P I T F A L L S
• A Steinmann pin can be inserted into
the disk space for intraoperative
radiographic localization; however, this
may injure a normal disk if inserted at
the wrong level.
FIGURE 20-10
A
FIGURE 20-11, A-B
B
Procedure
Step 1
n
Once portals are made and the lung retracted anteriorly with a fan retractor,
the disk space is located by tracing the rib to the spine.
n
Fluoroscopy or an anteroposterior thoracic spine radiograph can be taken
with a metallic instrument on the disk space to confirm the appropriate level
(Figure 20-12, A and B).
n
Adjacent segmental vessels can be retracted or cauterized, depending on the
extent of bony decompression.
n
The parietal pleura is widely dissected off the rib head and disk space using a
Harmonic scalpel (Ethicon Endo-Surgery) (Figure 20-13, A and B).
Procedure 20 | Endoscopic Thoracic Diskectomy 185
Rib head
A
FIGURE 20-12, A-B
Disc
Vertebral
body
B
A
FIGURE 20-13, A-B
B
186 Procedure 20 | Endoscopic Thoracic Diskectomy
Amputated
rib head
Pedicle
S T E P 2 P EA R L S
• A 5-mm burr may be used for more
aggressive decompression, depending
on surgeon preference.
S T E P 2 P IT FA L L S
• Bleeding may be encountered during
burring of the end plates and vertebral
bodies. Control is obtained with bone
wax on an endoscopic cotton-tipped
applicator.
Vertebral
Disc
body
FIGURE 20-14
n
The proximal 2 cm of the rib are removed with a pneumatic drill to expose the
lateral wall of the pedicle and neural foramen (Figure 20-14).
n
The pedicle is then drilled away to expose the dura of the spinal cord.
Step 2
n
Subsequent to removal of the pedicle and exposure of the neural foramen and
epidural fat, the posterior margin of the vertebral body is palpated, and the
superior and inferior end plates are drilled away (Figure 20-15).
n
Begin drilling from the posterior margin of the vertebral body to approximately
one third of the sagittal distance, leaving a cortical shell posteriorly to protect
the ventral aspect of the spinal cord.
n
The anterior two thirds of the vertebral body should be left intact.
n
The cephalad and caudad extension of the vertebral body decompression
depends on the size and migration of the herniated disk fragment.
S T E P 3 P EA R L S
• A dural leak can be directly repaired
with 6-0 Prolene sutures or patched
with fascia.
• In case of an unrepairable dural leak, a
lumbar drain should be inserted to
divert cerebrospinal fluid (CSF), and the
chest tube should be placed on
waterseal drainage.
S T E P 3 P IT FA L L S
• A persistent dural leak can develop into
a CSF-pleural fistula.
Step 3
n
Burr the tunnel to the opposite pedicle depending on the size of the disk
herniation.
n
Confirm the location of the burr with anteroposterior fluoroscopy.
n
Once burring is completed, the floor of the canal that is left as a cortical shell
can be removed with fine curettes or Kerrison rongeurs.
n
The portion of the disk that is not herniated and is between the vertebral bodies
is removed.
n
A rent is made in the posterior longitudinal ligament with a blunt probe or nerve
hook, and the ligament is subsequently resected with Kerrison rongeurs.
n
The remaining herniated portion of the disk is subsequently pulled into the
defect created by the bony decompression (Figure 20-16, A and B).
n
A calcified disk can be thinned with a burr to form a thin shell, which can be
cracked and pulled into the decompressed space. This allows complete decompression of the spinal cord without any manipulation (Figure 20-17, A and B).